Piston



in which'the pin 8` is seated. The pin 8 may Patented May 12, 1936 PATENT OFFICE-` 2,040,293 rrs'roN Henry Chandler, New York, N.`Y. v w Appiieaoon May 12, .1934, serial No. 725,276.

12 Claims. l((ll. 309-15) gThis invention relates to pistons and more particularly to pistons adapted for use in internal combustion engines.

In engines of the above type maintenance of proper piston clearance, cooling, piston weight, and wear of the cylinder'walls present major problems which are well known to persons skilled in the art. An object of the present invention is to provide a piston having characteristics which' take all of the above problemsinto consideration. Other objects are; to provide a light weight piston which is cheap and simple to construct and assemble, which maintains a minimum clearance at all operating temperatures, which facilitates lubrication of thecylinder walls and which minimizes wear'of the walls.-

Various other objects land advantages will be apparent as the nature of the invention is more fully disclosed.

Although the novel features which are believed to be characteristic of this invention will be pointed out more'particularly in the claims appended hereto, the invention itself as to its objects and advantages and the manner of its operation may be better understood by referring to the following description taken in connection with the accompanying drawing, in whicha preferred emrbodiment thereof is disclosed for purposes of illusjtration only. In the drawing the figure is a longitudinal section of a piston constructed in accordance with the present invention. I

Referring to the drawing more in detail the piston is shown as comprising a head I which may be formed of comparatively light metal such s aluminum and which may have a comparatively high coefiicient of expansion with respect to the metal ofthe cylinder walls.

and may be provided with oneor more grooves I Vin which rings 4 are seated, said rings being adapted to perform the usual functions of piston rings which are well known in the art. The head I is also provided with downwardly extending supporting members such as struts 5 having bosses 6 which are suitably enlarged and provided with bores 1 to receive a connecting rod pin 8. 4 A connecting rod 9 of the usual `construction may be provided with a head III having a bearing be secured to either the struts 5 or to the head I0 of the connecting rod 9 as may be desired;` AIn the form shown the pin rigidly secured in the struts 5 and thebearing II groove 20 for this purpose.

The piston head I is adapted to operate between cylinder walls `2 skirt and the cylinder wall.

I is adapted to 'bepermits pivotal movement of the piston rod 9 with respect thereto.

The struts 5 may extend downwardly past the I bosses 6 and may carry a ring I2 having shoulders I5 and flange I6 on which a retaining ring |1 is 5 threaded. 'I'he retaining ring is spaced from the shoulders I5 to form a groove 20 for the purpose to be described. Y `The piston is provided with a separate, cylindrical skirt or sleeve 2|, which may be formed 10 of the same material as the cylinder walls orA of a material having characteristics similar thereto, for example, of cast iron. The skirt 2| is adapted to be positioned in close contact with the walls, for example, with a clearance of the order 15 of .003 inch, and is provided with an internal rib 22 which is seated in the groove .20 between the shoulder I5 and the retaining ring I1. 'I'he rib 221s clamped between the shoulder I 5 and the retaining ring I1 against relative longitudinal 20 movement but may be suificiently free to permit relative radial movement in responseto dif. ferential expansion of the skirt 2| and the head I andto permit relative circumferential movement ofthe strut for seating purposes. Sulcient 25 clearance is provided between the shoulder I5 and the skirt 2| and between the rib 22 andthe 'I'he rib 22 thus acts as a gui@ for the head. 'Ihe 'struts 5 have l suiiicient leverage to limit the rocking movement" ofthe head without .constraining the parts against independent expansion.

`The skirt 2| extends axially above 'and below the rib 22 and is free to expand4 longitudinally as well as radially, independently of the expansion of-thecylindei` head.` The 'upper part of theskirt 2| overlaps a part of the head which is provided with a recess 25 to receive the same and with a groove 25 in which a sealing ring 21 vis seated. The ring 21 is adapted to bear against the inner 40 surfaceoftheskirtusoastomaintainatight seal 'therewith and tol act as a second guide for i the head.

The skirt forms ln eifect a large piston ringl o r sleeve having a small clearance whereby a tight seal is maintainedvdue to the oil film between the y Heat is transmitted- .throughthe struts 5 and 'the ring I2 to the skirt 2| and thence to the cylinder wall. Due to the large area of contact between the skirt and the cylinder wall, the transfer of heat is facilitated and the skirt remains at substantially the same ance will be maintained uniform regardless of the operating temperature.

The rings 4 prevent oil from passing to the top of the cylinder head I. The aluminum head may be formed with a comparatively large clearance inasmuch as the seal is not effected thereby and the skirt acts as a guide to prevent the head from slapping or rocking against the cylinder walls,

such clearance being essentiall in order to per-l when desired.

It is obvious that the location of the flange 22 may be changed and that the skirt 2| may be secured to the struts I5 by any suitable means. A

- preferred means has been shown for purposes of illustration only. Also, the ring I2 may be variously located and may be formed integral with the struts 5 or may be secured thereto as desired. In certain instances this ring may be discontinuous or may be coextensive with the struts.

Although a few of the operating advantages of the invention have been outlined above, various others will be readily apparent to a person skilled lin the art. It is to beunderstood that various changes and modifications may be made without departing from the scope of the invention which is only to be limiti i in accordance with the fol- "lowing claims .when interpreted in view of the prior art.

What is claimed is:

1. A two part piston comprising a head carrying bossesadapted to receive a connecting rod pin and a separate skirt having a diierent coefficient of expansion external to said head, a first guide means eiecting a fluid seal between said head and said skirt, a second guide means spaced axially therefrom to provide therewith a two point support for said skirt adapted to limit pivotal movement of said head therein, both of said guide means comprising frictionally held members having clearance with the head adapted to permit independent expansion of said parts, one only of said guide means having means to secure said parts against 'relative longitudinalv movement wherrby differential longitudinal expansion of said parts is permitted.

2. Altwo part piston comprising a head having depending struts carrying bosses adapted to rev ceive a connecting rod pin and a separate skirt having a different .coefiicient of expansion external to said head, a iirst guide means effecting a fluid seal between said head and said skirt, a second guide means associated with said struts below said bosses to provide with said rst guide means a two point support for said skirt adapted to limit pivotal movement of said head therein,

' both of., said guide means comprising frictionally held members having clearance with the head .adapted to permit independent expansion of said parts and to permit free rotation of said skirt for seating in a cylinder, one only of said guide means having means to secure said parts against relative longitudinal movement whereby 4diierential longitudinal expansion of said parts is permitted.

3. A two part piston comprising a head having depending struts carrying bosses adapted to receive a connecting rod pin and a separate skirt having a diierent coeincient of expansion overlapping atleast a part of said head, means effecting a fluid seal' between said part and said skirt, means associated with said struts below said bosses to engage said skirt, said first and second means effecting a two point support for said skirt adapted tolimit pivotal movement of said head therein, both of said means having a clearance relative to the head suicient to permit independent expansion of said parts, one only of said means having means to secure said parts against relative longitudinal movement whereby differential longitudinal expansion of said parts is permitted.

4. A two part piston comprising a head having depending struts carrying bosses adapted to receive a connecting rod pin and a separate skirt having a different coeiiicient'7| of expansion overlapping at least a part of said head, means effecting a iluid seal between said part and said skirt, guide means comprisinga radial groove in said struts below said bosses, and a cooperating radial ange formed on said skirt, said rst and second means providing a two point support for said skirt adapted to limit pivotal movement of said head therein, both of said means having a clearance relative to the head suicient to permit independent expansion of said parts, said guide means having means to secure said parts against relative longitudinal movement, said sealing means being adapted to permit relative longitudinal movement whereby differential longitudinal expansion of said parts is permitted.

.5. A two part piston comprising a head having depending struts carrying bosses adapted to receive a connecting rod pin and a separate skirt having a different coeiiicient of expansion overlapping at least a part of said head and having suflicient clearance relative to the head to permit independent expansion of said parts, a sealing ring carried `by said head and engaging said skirt, an annular member carried by said struts below said bosses and having a radial groove, a ange carried by said skirt and held in said groove against longitudinal movement, said ange being free to rotate or expand independently of said struts, wherebyv the entire skirt is adapted to seat in a cylinder and whereby said head is constrained fortransverse movement within said skirt but is free to expand independently of said skirt. 6. A two part piston comprising a head carrying bosses adapted to receive a connecting rod pin and a separate skirt having a diierent coefcient of expansion external to said head, means associated with said head to support said skirt at two axially spaced points so as to limit pivotal movement of said head, both of said means comprising frictionally held members having clearance with the head adapted to permit independent expansion of said parts, one only of said means having means to securesaid parts against relative longitudinal movement whereby diierential longitudinal expansion of said parts is permitted.

7. A two part piston comprising a head having depending struts carrying bosses adapted to re- 

